This invention pertains generally to multicolor electrographic recording devices. In particular, the present invention is a clamping and tensioning system for securing a sheet of photoconductor film to an outer circumferential surface of a carrier drum.
Typically, to produce a multicolor print a photoconductor film secured to a carrier member of the electrographic recording device is first charged to a uniform potential to sensitize its imaging surface. The charged surface of the photoconductor film is exposed to an image of an original document that is to be reproduced as a multicolor print. This procedure allows the photoconductor film to record an electrostatic latent image corresponding to the informational areas contained within the image of the original document.
To form a multicolor print, successive images of the original document are digitally color separated through different colored filters and recorded on the photoconductor film. These latent images are developed with different colored liquid toners supplied from corresponding toner developing modules of a toner handling network. The color of the liquid toner in a particular developing module corresponds to the subtractive primary of the color of the respective digitally separated image. Electrographic recording is normally done with yellow, cyan and magenta liquid toners. Usually the electrographic recording device also includes a developing module having black liquid toner, since it is required in virtually all commercial color printing applications. The different colored developed images are transferred from the photoconductor film to a print medium in superimposed registration with one another. Heat is usually applied to permanently fuse the image to the print medium to form a completed multicolor print.
A mechanism for securing a photosensitive sheet to an outer surface of a rotary drum is disclosed in U.S. Pat. No. 4,682,881 to Komatsubara et al. The outer surface of the rotary drum includes an image forming section to which the photosensitive sheet is attached and a non image forming section. The image forming section has a plurality of sucking holes arranged along the longitudinal extent of the rotary drum. The sucking holes are connected to a sucking duct through a connecting pipe. A blower coupled to the sucking duct provides vacuum pressure through the sucking holes, and thereby ensures that the photosensitive sheet is firmly secured to the outer surface of the rotary drum during the developing process.
It is evident that there is a continuing need for an improved clamping and tensioning system for securing a sheet of photoconductor film to an outer circumferential surface of a carrier drum. In particular, there is a need for a clamping and tensioning system which permits one person to reliably install and uniformly tension the photoconductor film about the outer surface of the carrier drum. In addition, the clamping and tensioning system should allow the tension in the photoconductor film to be varied depending upon the type and thickness of the particular photoconductor film used in the developing process. Moreover, the clamping and tensioning system should effectively ground the photoconductor film to the carrier drum and should be convenient-to-use.